82 research outputs found
Digoxin reveals a functional connection between HIV-1 integration preference and T-cell activation
HIV-1 integrates more frequently into transcribed genes, however the biological significance of HIV-1 integration targeting has remained elusive. Using a selective high-throughput chemical screen, we discovered that the cardiac glycoside digoxin inhibits wild-type HIV-1 infection more potently than HIV-1 bearing a single point mutation (N74D) in the capsid protein. We confirmed that digoxin repressed viral gene expression by targeting the cellular Na+/K+ ATPase, but this did not explain its selectivity. Parallel RNAseq and integration mapping in infected cells demonstrated that digoxin inhibited expression of genes involved in T-cell activation and cell metabolism. Analysis of >400,000 unique integration sites showed that WT virus integrated more frequently than N74D mutant within or near genes susceptible to repression by digoxin and involved in T-cell activation and cell metabolism. Two main gene networks down-regulated by the drug were CD40L and CD38. Blocking CD40L by neutralizing antibodies selectively inhibited WT virus infection, phenocopying digoxin. Thus the selectivity of digoxin depends on a combination of integration targeting and repression of specific gene networks. The drug unmasked a functional connection between HIV-1 integration and T-cell activation. Our results suggest that HIV-1 evolved integration site selection to couple its early gene expression with the status of target CD4+ T-cells, which may affect latency and viral reactivation
Biomarker candidates of neurodegeneration in Parkinsonâs disease for the evaluation of disease-modifying therapeutics
Reliable biomarkers that can be used for early diagnosis and tracking disease progression are the cornerstone of the development of disease-modifying treatments for Parkinsonâs disease (PD). The German Society of Experimental and Clinical Neurotherapeutics (GESENT) has convened a Working Group to review the current status of proposed biomarkers of neurodegeneration according to the following criteria and to develop a consensus statement on biomarker candidates for evaluation of disease-modifying therapeutics in PD. The criteria proposed are that the biomarker should be linked to fundamental features of PD neuropathology and mechanisms underlying neurodegeneration in PD, should be correlated to disease progression assessed by clinical rating scales, should monitor the actual disease status, should be pre-clinically validated, and confirmed by at least two independent studies conducted by qualified investigators with the results published in peer-reviewed journals. To date, available data have not yet revealed one reliable biomarker to detect early neurodegeneration in PD and to detect and monitor effects of drug candidates on the disease process, but some promising biomarker candidates, such as antibodies against neuromelanin, pathological forms of α-synuclein, DJ-1, and patterns of gene expression, metabolomic and protein profiling exist. Almost all of the biomarker candidates were not investigated in relation to effects of treatment, validated in experimental models of PD and confirmed in independent studies
Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.
In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field
Time to reconfigure balancing behaviour in man: changing visual condition while riding a continuously moving platform.
While balancing on a continuously anteroposterior
(A-P) translating platform (10 cm, 0.5 Hz),
the head normally oscillates with the platform without
vision but is stabilized in space with vision. We estimated
the time to shift from one to the other balancing
behaviour when visual condition changed at some
stage during the balancing trials. Ten subjects performed
randomly 50 balancing trials (each lasting 18 s):
10 trials with eyes open (EO), 10 with eyes closed
(EC), 15 in which participants started with EO and
closed their eyes (condition EO!EC) in response to
an acoustic signal delivered during the trial, and 15
starting with EC and closing their eyes (EC!EO) in
response to the same signal. No other speciWc instruction
was given. Displacements of malleolus, hip and
head, and EMG from leg and axial muscles were
recorded. Indexes of amplitude of A-P head and hip
oscillation and of amplitude of EMG activity were
computed. All variables were larger with EC than EO.
On changing visual condition during the trial, the pattern
of head and hip movement and of muscle activity
turned into that appropriate for the new visual condition
in a time-interval ranging from about 1 to 2.5 s.
For each subject, the mean latency of the change in the
balancing behaviour was assessed by statistical methods.
On average, the latencies of kinematics and EMG
changes proved to be longer for the EO!EC condition
than viceversa. Further, the latencies of the
changes were also measured across all EO!EC and
EC!EO individual trials. These values were clustered
around particular epochs of the Wrst few oscillation
cycles following the shift in visual condition. The
results show that subjects can rapidly adapt their balancing
behaviour to the new visual condition. However,
they appear to refrain from releasing the new
behaviour were this unWt, and unfastened it at appropriate
time in the next platform translation cycle.
These Wndings reveal the temporal and spatial features
of the automatic release of the new balancing strategy
in response to a shift in the ongoing sensory set, and
emphasize the swiftness in the change in balancing
behaviour when subjects pass from a non-visual to a
visual reference frame
The control of equilibrium in Parkinson's disease patients: delayed adaptation of balancing strategy to shifts in sensory set during a dynamic task
Processing of sensory information, timing operations and set-shifting can be
affected in Parkinson's disease (PD) patients. We investigated their capacity and
swiftness to pass from a kinaesthetic- to a vision-dependent behaviour during
dynamic balancing on a continuously moving support base. Nineteen on-phase PD
patients and 13 age-matched normal subjects stood on a platform continuously
translating in the antero-posterior direction at 0.2 Hz. Body segment
oscillations were identified by a stereophotogrammetric device and electromyogram
(EMG) was recorded from tibialis anterior and soleus. Under constant visual
conditions, both patients and normal subjects roughly stabilised head and trunk
in space with eyes open (EO) but followed the platform displacement with eyes
closed (EC). Amplitude and variability of the periodic EMG bursts were smaller
with EO than EC. Constant visual-condition trials were intermingled with trials
in which subjects opened (EC-EO) or closed (EO-EC) the eyes in response to an
acoustic signal. Both patients and normal subjects changed kinematics and EMG
patterns to those appropriate for the new visual condition. However, PD patients
were slower in changing their behaviour under the EC-EO condition. These findings
show abnormal temporal features in balancing strategy adaptation when shifting
from kinaesthetic to visual reference in PD. The delay in the implementation of
the vision-dependent behaviour was unexpected, given the advantage vision is
supposed to confer to motor performance in PD. This condition may play a major
role in the instability of patients performing dynamic postural tasks under
changing sensory conditions
Post-effect of forward and backward locomotion on body orientation in space during quiet stance
Neural circuits responsible for stance control
serve other motor tasks as well. We investigated the eVect
of prior locomotor tasks on stance, hypothesizing that postural
post-eVects of walking are dependent on walking
direction. Subjects walked forward (WF) and backward
(WB) on a treadmill. Prior to and after walking they maintained
quiet stance. Ground reaction forces and centre of
foot pressure (CoP), ankle and hip angles, and trunk inclination
were measured during locomotion and stance. In WF
compared to WB, joint angle changes were reversed, trunk
was more Xexed, and movement of CoP along the foot sole
during the support phase of walking was opposite. During
subsequent standing tasks, WB induced ankle extension,
hip Xexion, trunk backward leaning; WF induced ankle
Xexion and hip extension. The body CoP was displaced
backward post-WB and forward post-WF. The post-eVects
are walking-direction dependent, and possibly related to
foot-sole stimulation pattern and trunk inclination during
walking
Head stabilization on a continuously oscillating platform: the effect of a proprioceptive disturbance on the balancing strategy
When standing and balancing on a continuously and predictably moving platform,
body equilibrium relies on both anticipatory control and proprioceptive feedback.
We have vibrated different postural muscles of the body to assess any effect of
confounding the proprioceptive input on balance during such unstable conditions.
Low and high platform oscillation frequencies were used, because different
strategies are used to withstand the two perturbations. Eyes open (EO) and closed
(EC) conditions were also tested, to assess whether the stabilizing effect of
vision is independent from the proprioceptive disturbance. Subjects (n = 14)
performed two series of trials, EO and EC: (1) quiet erect stance, (2) stance on
the platform translating at 0.2 or 0.6 Hz sinusoidally in the anteroposterior
(A-P) direction (dynamic conditions). Continuous bilateral vibration (90 Hz) was
produced by two vibrators fixed to the following homonymous muscles: dorsal neck,
quadriceps, biceps femoris, tibialis anterior, and triceps surae. Acquisition of
body segments' displacement began 10 s after the start of platform translation.
From markers fixed to head, hip, and malleolus, we computed the A-P oscillation
of head and hip, body orientation in space, and cross-correlation (CC) and
time-delay between malleolus and head trajectories. The results were (a) the head
A-P oscillation was smaller with EO than EC, under both quiet stance and dynamic
conditions; (b) vibration of tibialis and triceps surae, but not of other
muscles, slightly increased head and body A-P oscillation with EC under dynamic
conditions; (c) at 0.2 Hz but not at 0.6 Hz, for all visual and vibration
conditions, there was a significant association between head and feet; (d) at 0.2
Hz, EC, neck muscle vibration increased this association, whereas vibration of
the other muscles induced a major time delay in the oscillation of head compared
with feet; (e) vibration of either neck or tibialis induced forward body leaning,
while vibration of either triceps surae or biceps femoris induced backward
leaning, with both EO and EC, under both static and dynamic conditions; (f) the
head A-P oscillation, however, under dynamic conditions was not dependent on body
leaning. The relatively scarce effects of proprioceptive disturbance on head
stabilization and multijoint coordination (in spite of effects on body
orientation similar to those observed during stance) speak for a major role of
anticipatory control in the dynamic equilibrium task. However, the significant
vibration-induced time delay in segments' coordination at low translation
frequency, EC, suggests that the normally patterned Ia input promotes continuous
adjustments of the feed-forward control mode
Head stabilization on a continuously oscillating platform: the effect of a proprioceptive disturbance on the balancing strategy.
When standing and balancing on a continuously
and predictably moving platform, body equilibrium
relies on both anticipatory control and
proprioceptive feedback. We have vibrated different
postural muscles of the body to assess any effect of
confounding the proprioceptive input on balance during
such unstable conditions. Low and high platform oscillation
frequencies were used, because different strategies
are used to withstand the two perturbations. Eyes open
(EO) and closed (EC) conditions were also tested, to
assess whether the stabilizing effect of vision is independent
from the proprioceptive disturbance. Subjects
(n=14) performed two series of trials, EO and EC: (1)
quiet erect stance, (2) stance on the platform translating
at 0.2 or 0.6 Hz sinusoidally in the anteroposterior (A-P)
direction (dynamic conditions). Continuous bilateral
vibration (90 Hz) was produced by two vibrators fixed
to the following homonymous muscles: dorsal neck,
quadriceps, biceps femoris, tibialis anterior, and triceps
surae. Acquisition of body segmentsâ displacement began
10 s after the start of platform translation. From
markers fixed to head, hip, and malleolus, we computed
the A-P oscillation of head and hip, body orientation in
space, and cross-correlation (CC) and time-delay between
malleolus and head trajectories. The results were
(a) the head A-P oscillation was smaller with EO than
EC, under both quiet stance and dynamic conditions; (b)
vibration of tibialis and triceps surae, but not of other
muscles, slightly increased head and body A-P oscillation
with EC under dynamic conditions; (c) at 0.2 Hz
but not at 0.6 Hz, for all visual and vibration conditions,
there was a significant association between head and
feet; (d) at 0.2 Hz, EC, neck muscle vibration increased
this association, whereas vibration of the other muscles
induced a major time delay in the oscillation of head
compared with feet; (e) vibration of either neck or tibialis
induced forward body leaning, while vibration of
either triceps surae or biceps femoris induced backward
leaning, with both EO and EC, under both static and
dynamic conditions; (f) the head A-P oscillation, however,
under dynamic conditions was not dependent on
body leaning. The relatively scarce effects of proprioceptive
disturbance on head stabilization and multijoint
coordination (in spite of effects on body orientation
similar to those observed during stance) speak for a
major role of anticipatory control in the dynamic equilibrium
task. However, the significant vibration-induced
time delay in segmentsâ coordination at low translation
frequency, EC, suggests that the normally patterned
Ia input promotes continuous adjustments of the
feed-forward control mode
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